LAARS SC 12 - Install and Operating Manual - Manual (Page 10)

Page 10 LAARS Heating Systems
ADJUSTING THE CONTROL SETTING
• After the power up routine is complete, the display will show the system water temperature.
• To display the other control settings, repeatedly press the center SELECT SETTING button.
• A setting can only be adjusted when it is being displayed.
• Use the UP and DOWN buttons to adjust the setting.
• The display will always revert back to the actual system temperature after 30 seconds.
• Select the appropriate page from the list below for the available control settings for your
application:
Set Point Control with Normal Sequencing Temperature or External Set Point pg. 10
Set Point Control with Oversize System Sequencing Temperature or External Set Point pg. 11
Outdoor Reset Control with Normal Sequencing pg. 12
Outdoor Reset Control with Oversize System Sequencing pg. 13
SET POINT CONTROL WITH NORMAL SEQUENCING
Dip Switch 8 - OFF
Press SELECT
Button
DISPLAY Press and hold either the UP or DOWN button to adjust
Once
Set Point
The Set Point is the temperature which the SC will sequence stages to hold. Note that if you are
using the External Set Point, you will not be able to change the Set Point unless you adjust the 4-
20mA input. The Set Point is adjustable between -30°F to 250°F. Default is 70°F.
Twice♦
Outdoor Temp
This is the outdoor sensor temperature value.
3 Times♦♦
Outdoor Cutoff
Available only when the outdoor sensor is installed. When the outdoor temperature falls below the
Outdoor Cutoff value, the SC will activate stages for heat. The Outdoor Cutoff can be set ON or OFF
and from 40 to 100°F. Default is 60°F.
3 or 4 Times
Reaction Time
The Reaction Time controls the minimum run time for a stage (1/2 the Reaction Time). Also, it con-
trols how long should a stage run before it activates/subtracts another stage. It is adjustable from half
a minute (0.5) to 8.0 minutes. Default is 2 minutes.
4 or 5 Times
System Delay
The System Delay controls how long the System relay will remain energized after the last Output has
been turned off or the outdoor temperature rises above the Starter. The System Delay is adjustable
from 0 to 30 minutes. Default is 0.
5 or 6 Times
Purge Time
The Purge Time should be set to the length of the unit’s purge cycle. The Purge Time will apply
when any ON/OFF unit is activated. On multiple stage units, the Purge Time will only apply to the Lo
stages. The Purge Time is adjustable from 0.0 to 10.0 minutes. Default is 0.
6 or 7 Times
Boiler runtime
This is the minimum amount of time any boiler will run after the Purge cycle has been completed. This
timer does not apply when only one stage is running, the Last Stage Hold
LSH applies in that case.
The Boiler Runtime is adjustable between 0 to 60 minutes. Default is 0.
7 or 8 Times♦♦
Program Offset
The Programmed Offset fi ne tunes the External Set Point. With a known 4mA input, the offset can be
set to make the External Set Point 110°F. The Program Offset is adjustable between -10°F to +10°F.
Default is 0°F.
7 or more Times
Last Stage Hold
To prevent short cycling of the last stage in low load conditions, the system temperature can exceed
the Set Point by the amount selected by the Last Stage Hold before the last stage is turned off. The
Last Stage Hold is adjustable between 0°F to 20°F. Default is 10°F.
8 or more Times♦♦
Setback
The Setback adjusts the number of degrees the Set Point water temperature will be reduced when
Input terminals 7 and 8 are closed. If the Setback is set to 0, then the system will Shutdown on a
closure. The Setback is adjustable from 0°F to 40°F. Default is 0°F.
8 or more Times♦♦
DHW Priority Time
Only available when the System Output is set to System Pump (dip switch 1 is ON and dip switch 6 is
OFF ) This setting adjusts the amount of time the System relay output will remain off during a DHW
call. If the DHW call is not satisfi ed before the DHW priority time has elapsed, the System relay will
energize to provide heat. The DHW Priority is adjustable from 0 to 4 hours in half hour increments.
Default is 0.
8 or more Times♦
Default
The SC returns to the default display of system water temperature.
♦ Actual temperature values are not adjustable
♦♦ May not be available, depending on status of the outdoor sensor and dip switches.
SELECT
SETTING
UP
DOWN
Press and
Hold to
Adjust
Press to Scroll
Through Control
Settings
Control Settings
Display